Posted
by
timothy
on Sunday November 03, 2013 @02:02AM
from the let's-stay-out-of-the-actual-blast-radius dept.

sciencehabit writes "The last star to go supernova in the Milky Way—that astronomers know of—exploded in 1604, before Galileo first turned a telescope to the heavens. But with a neutrino detector now being built within a Japanese mountain that could come online as early as 2016, researchers might be able to do something as yet undone: Make detailed observations of a supernova in our galaxy before it visibly explodes. First, astronomers would be alerted to the unfolding event by the flood of neutrinos generated when a supernova collapses. Within minutes, they could determine the general area of the sky where the explosion would occur, point their infrared telescopes in that direction, and wait for the fireworks. With the new sensor in place, instruments—especially infrared telescopes—would have an almost 100% chance of observing the next supernova in our galaxy, the researchers report."

If you want to feel small go out in your back yard in the summer (not near the 4th of July) and look up at the sky. Turn off the porch light, and if you have to - ask the neighbors to turn off theirs. This is the Milky Way.
You'll see a cloud that goes beyond what you can see, each point in it another sun with worlds like our own. We fight over square miles, and here are whole worlds beyond number, so common that your eye cannot put one from the other.

If you want to look at it that way, mass and our own short lifespans are our worst enemies.

With less mass we could move faster. With longer lifespans, speed would be less important.

It's only when we are so constrained by mass and time, and other things like need for oxygen and food, that area of land matters at all. There's an amazing amount of universe out there just waiting for us to get our act together.

I assume you meant no disrespect, but "Mass" begins with a capital "M". At Mass, my brain is in fact less constrained by its need for oxygen. I pray for my own short lifespan to become greater so I can attend even more sessions of Mass. I agree there's an amazing amount of universe out there and we do need to get our act together. We need to speedily apply forces to our worst enemies and make aliens spend their time at Mass too.

We fight over square miles, and here are whole worlds beyond number, so common that your eye cannot put one from the other.

While I appreciate the sentiment, the fact is those other worlds beyond number are REALLY hard to reach, and not everyone appreciates the sentiment.

It's like we're in a playground with a lot of bullies and a limited supply of goods, and every year there are more of us and more bullies, but not any more goods--we just occasionally figure out how to use them better. It doesn't matter how big the world is, or how many worlds there are, if we can't breach the walls of our playground and make it across the inte

If you want to feel small go out in your back yard in the summer (not near the 4th of July) and look up at the sky. Turn off the porch light, and if you have to - ask the neighbors to turn off theirs. This is the Milky Way.

If you live in a moderately sized city, you're going to have to ask quite a few "neighbors" to shut off their "porch lights" before you can see the Milky Way.

If the supernova that this detector is designed to spot comes from within our galaxy, as they are looking for, then the star that exploded did so less than 100,000 years ago (approximately). That is well within the lifespan of our solar system.

Our sun is not likely to generate a supernova, as it has too little mass. Because there is no companion star in orbit of our sun, it is not even likely to go nova. The expectation is that several hundred million, or a billion or so years from now the sun will run out of hydrogen and switch to burning helium. At that time the energies involved will cause the sun to grow to become a red giant, which is likely to have consumed both Mercury and Venus, and possibly Terra as well. Once the energy of that process is released, (i.e. the sun runs out of Helium) the sun will collapse to a white dwarf, that will be about the size of the earth. It will continue to consume whatever remaining Hydrogen and Helium atoms are in it, but unless it collides with another star or star remnant, that's going to be the end of it's energy releasing days.

As to it destroying all traces of our existence, not so much. Even if everything in orbit and on the moon, and even the planet earth itself are destroyed, we have a lander on Titan that is likely to survive, several landers on Mars that may still be recognizable, and several interstellar missions that will still be moving. Voyager 1 is currently traveling at 17km/s, or 61,200km/h. (Which does exceed escape velocity for the sun.) While that speed will drop over time before the gravity of the sun is overcome by the gravity of other stars that will affect the flight path of Voyager 1, it is not expected to drop below 10km/s or 36,000km/h. At that speed it will travel 315,360,000 kilometers per year, a little over 1051 light seconds. (over 17 light minutes.) It will take over 1,800,000 years to travel a light year. In 100 million years it will be over 40 light years from the sun. While that may not be any great shakes as far as intergalactic distances go, it's definately far enough to avoid the effects of even a supernova if our sun were massive enough to go that route. It is possible that it will be destroyed by other stars going supernova in that time, or more likely later, but that is not a given. So even if we don't get off this rock, which I sincerely hope we can accomplish before we destroy ourselves, I expect that there will still be a trace of our existence in the universe.

I think you are off by two orders of magnitude on the voyager data. Assuming you are correct that it will be coasting at around 10km/s, the speed of light is about 3x10^8 m/s or 3x10^5 km/s so voyager will travel a light year in approximately 3x10^4 = 30,000 years, not 1.8 million years. In 100 million years it will have traveled ~3,333 light years.

You may be right. Though 3k light years seems a bit far to me, even in 100 million years. But then no matter whether it's 40 light years, or 3k light years, what happens to our sun at that point is unlikely to have much of an impact on Voyager 1. In any case, the path Voyager takes is not going to be a straight line, even between galaxies should it be traveling that far.

The expectation is that several hundred million, or a billion or so years from now the sun will run out of hydrogen...

Make that slightly more than five billion years. Although, a few hundred million years from now, Earth will be a nasty place anyway, because of the fairly regular 1% increase in solar luminosity per every 100 My.

....and switch to burning helium. At that time the energies involved will cause the sun to grow to become a red giant, which is likely to have consumed both Mercury and Venus, and possibly Terra as well.

You mean that a helium flash will occur. But isn't that actually supposed to happen AFTER the Sun becomes a red giant? I think it is.

Once the energy of that process is released, (i.e. the sun runs out of Helium) the sun will collapse to a white dwarf, that will be about the size of the earth. It will continue to consume whatever remaining Hydrogen and Helium atoms are in it, but unless it collides with another star or star remnant, that's going to be the end of it's energy releasing days.

Again, vastly simplified and potentially misleading.

it is not expected to drop below 10km/s or 36,000km/h. At that speed it will travel 315,360,000 kilometers per year, a little over 1051 light seconds. (over 17 light minutes.) It will take over 1,800,000 years to travel a light year.

Your numbers are somewhat off, because 1,800,000 years at 10 km/s actually gives sixty light years. Obviously, the figure can become substantially different depending of the actual trajectory.

I was trying to keep it simple. I'm not an astrophysicist, don't have the references necessary handy, and so on. As far as the calculations being off, I'd far rather in this case have calculated on the low side than on the high side. If everyone keeps correcting me by pointing out that my calculations are low, it just supports the conclusion that we'll be even farther out there than people expected.

Essentially my statement is that when the sun 'goes' we may see the loss of the planet earth, and all that we'

When I read news like this, my lousy programming job that pays 80k a years, seems like a total bullshit, compared to this.

If you feel this way, you should realize that it's never too late to go back to university, get a PhD and join the research effort in some capacity. You'll likely find that you won't earn as much as an academic than if you had stuck to a career in programming, but your work will be more interesting and fulfilling.

When I read news like this, my lousy programming job that pays 80k a years, seems like a total bullshit, compared to this.What makes me even sadder...... those super novas are so far away, and might have existed even longer than earth and our solar system.One day, our sun will go up in flame, and not even a trace of our existence will be left behind.

That will happen in about 2-5 biillion years. Even if mankind went extinct today, Voyager 1/2, Pioneer 10/11 and New Horizons will still exist (as well as the third stage booster from New Horizons), and likely continue to exist until the heat death of the universe.

Novas , less than super, produced by Chevrolet from 1962 -1988 tend to leak oil, wear rings out and rust. It was not marketed in Mexico as the Nova or No Va (no go in Espanol) rather it was the Omega ( the last car anyone would want to be stuck with) the Mexicans cursed.If the sun goes up in flames, certainly we hope Chevrolets budget offerings go with it.Revere your work, pat yourself on the back, you have more on the ball than Chevrolet and your code may live beyond the life of a Nova.Meanwhile you can ti

So are you gonna run out and buy a car called constupatedslug ? I would suggest that NOVA appears more conspicuously in Espanol,than NOTABLE does in English. Urban legend or not, I've known Mexicans with that already pre installed in their heads. They actually don't like the idea.But feel free to try again.

Well, judging from the debt rate of UA and European States, we will get to build such a device.

Japan, actually engages in fueling their economy with debt-money, (we have seen similar matters in UA and EU States, subsidized new car programm "for the environment")

Keep in mind Japan has 200% debt rate, so the total amount of goods and money generate in the country is only half of the debt value, but it's Japan sourced debt.All japanese people own japan two times;)

No not really, ask yourself one question, do you own anything that says "Made in Greece" or anything that says "Made in Japan".

Nobody wants to give greece money anymore. This has some causes, but all accumulate into one big cause, greece does not produce much and has an overblownmilitary complex. They wanted to "fragg" the turks in the past but then they stepped down and collected & displayed tanks as their sign of strength.(try some digging, calculate the "tanks per people" ratio, and compare that to o

Well, if you look at how Japan screwed up the powerful economy it had in the 70s and early 80s, they aren't going to have a lot of reserve for future problems. They'll need to do something or that debt and related problems will catch up with them.

It's good that the Japanese are funding this, because at the rate European and US basic research funds are going, I doubt we'll be able to detect much of anything by 2016...

If any of this was important to you, you could try funding it yourself with the help of like-minded people. My take is that everyone in the world right now is going through an entitlement binge. That's going to mean less public funding of basic research and other such stuff, globally.

I suppose we could just give up and let whoever still can suck from the public teat do all the research, or we can just find other sources of funding and keep going. Assuming, of course, that this actually is important to yo

There are several features that you need to detect supernovae with neutrinos: good direction resolution, large enough mass to detect multiple neutrinos from the supernova and low enough energy sensitivity. Detectors like IceCube have a huge mass (1 km^3 of ice) and good directional accuracy but they cannot detect the low energy neutrinos from a supernova. Other detectors in the list use chemical methods (neutrinos will cause inverse beta decay) but these have the mass and energy sensitivity but give no directional information. This is the first experiment to have the right mix of all the parameters.

What do you mean "indirectly"? We detect them via their direct interaction with matter. This is the same as it is for every other particle that we can detect. The only difference is that neutrinos do it far less often than most others.

Kinda sorta. Their existence has been inferred by experimental results.

Here is a nicely written neutrino primer for humans [t2k-experiment.org] that answers your detection question. If you already know everything about the subject, visit the Wiki neutrino page [wikipedia.org] to learn what you already know, revel in the obviousness of it all and have a good chuckle at the expense of folks like me who find it to be very jargony.

I first learned of neutrinos while doing web research on Neapolitan ice cream [wikipedia.org]. This amazing ice cream has three flavors, and it appears that neutrinos also have three flavors. This cannot be a coincidence. Since any unified theory which does not include ice cream must be incomplete, I see this as evidence that we are close to solving some great puzzle.

If you are at a cocktail party and overhear particle physicists in a discussion of the "Solar Neutrino Problem", step right up and say that it was Mean Mr. Sun who ate all the chocolate, leaving us to detect only the yucky vanilla and strawberry -- he even left the spoon in the freezer! You will be greeted with smiles and knowing glances, and they might even invite you on the road to tour with them. Particle physicists are always surrounded by groupies and hot women.

Kinda sorta. Their existence has been inferred by experimental results.

The existence of every single particle we know of has been inferred from experimental results: neutrinos are no different. So the correct answer is "Yes, neutrinos have been detected" unless you are going to use the same uncertainty for things like the quarks, muons, Higgs boson etc. etc.

It's hard to say that they're indirect detections. How do we even detect something like an electron? By the fundamental forces like electromagnetism, which is no different in principle from the methods used to detect neutrinos, which work by weak nuclear force interactions. The trouble is that neutrinos are affected only by gravity and the weak nuclear force (making them an example of a dark matter WIMP), so detecting them is rather hard, given that the forces involved are so weak.

Human activity generates a staggering number of neutrinos/sec. From this article [wikipedia.org]:

"Thus, an average [4000 MWth, 1300MWe] nuclear power plant may generate over 10^20 antineutrinos per second above this threshold [1.8MeV], but also a much larger number (97%/3% = ~30 times this number) below the energy threshold, which cannot be seen with present detector technology." That's 3.1x10^21 neutrinos/sec for each 4GWth reactor!

Also, from the same reactor, "... 185 MW is radiated away as antineutrino radiation and nev

The article is technically accurate but this isn't anything new. And yes, neutrinos will arrive before the light from an exploding supernova. There is already a large detector filled with heavy water that can do this in Sudbury, Ontario, Canada. It has been around for a decade. And this is one of the things it is advertised to do.

So then you'd agree with me. The supernova occurred 20,000 light years away and the light reached Earth in 1604.

The only reference frame in which the supernova also exploded in 1604 is that of a photon making the trip. To us on Earth, it happened as long ago as it takes for the light to reach us (ignoring the negligible expansion of space between the two points in that time).

The last star to go supernova in the Milky Wayâ"that astronomers know ofâ"exploded in 1604,

Leaving aside the quibbles about the date of the explosion compared to the date of the light reaching the Earth, this still isn't true. There was likely a supernova in the disc of the galaxy (whose light reached Earth) in the 1870s or 1880s. But since it was on the far side of a dense gas/ dust cloud, it wasn't visible. It's only in the last few years that IR telescopes and radio telescopes have managed to d